TM 9-4110-255-14
WARNING
Never use a heating torch on any part that contains refrigerant. Heat may cause the refrigerant
to decompose and release irritating, toxic, and corrosive gases. All refrigerant must be
discharged from the system and the entire system must be purged with dry nitrogen before
beginning any brazing operation.
Debrazing a joint when the system is pressurized can result in personal injury.
CAUTION
If heat is applied slowly, or only on one side, the entire component or length of tubing will be
heated and filler alloy in adjacent joints may also be melted.
Brazing a joint without nitrogen flowing through the tubing, will cause deposits to form on the
inside of the tube and may cause obstructions in the refrigeration system or equipment
damage.
(3)
Check that the system is being purged (para 5-11) and that no pressure is being built-up in the system.
Apply sufficient heat uniformly around the joint to quickly melt the filler alloy. Remove heat as soon as
the joint is separated.
b.
Clean. All filler alloy must be cleaned from debrazed joints before reassembly. Heat each piece of the joint
until the filler is melted and then wipe it away with a wire brush. Be sure no filler alloy or other debris is left
inside any tubing, fitting, or component. Use abrasive cloth as necessary to clean joints.
c.
Braze.
(1)
Protect wiring harnesses and other components with appropriate heat shields.
NOTE
All joints, except those provided with flare fittings, are made by brazing in accordance with
MIL-B-7883, except that radiographic examination is not required.
Grade IV or VI brazing alloy and Type-B flux, as specified in MIL-B7883, must be used for all
copper to brass joints. Grade III brazing alloy may be substituted for Grade IV or VI for copper
to copper joints, flux is not required for copper to copper joints.
(2)
If brazing a joint on a valve, disassemble the valve to the extent possible and wrap all but the joint with
a wet rag to act as a heat sink.
5-19
